1. Field of the Invention
The present invention relates to a method of making a light-emitting-diode (LED) array head for use in semiconductor device manufacturing, and in particular to a simplified connection between each electrode of the array element and exterior wiring without using gold wire therebetween during manufacturing of the LED array on a substrate such as ceramic material.
2. Brief Description of Prior Arts
As data processing capacity of computers increase continuously these days, a printer as its data outputting device is also required to make its printing speed high and have high-resolution and multiple functions. As a result, for such a requirement, there has been often used an LED printing system utilizing an LED array head having a great number of light emitting components, thereby obtaining high resolution of printing quality. Generally, such an LED array head can be constructed with a large-scale integration of light-emitting-diodes (LEDs). Hence those LED arrays are mostly made onto a ceramic substrate, which fabricating process is known to be very difficult to do.
FIG. 1 shows a portion of a known LED array for the above described object, wherein a reference numeral 1 is a GaAs-substrate, 2 is a GaAsP-film, 3 is an insulating film, 4 is a zinc-diffusion region, 5 is a P-type individual electrode of LED, 6 is an N-type common electrode, and 7 is a light-emitting surface. When a voltage is applied to the N-type common electrode 6 and the P-type individual electrode 5 of the LED, light emission is made through the surface 7. These LED arrays can be arranged in order as shown in FIG. 2, because the P-type individual electrode 5 is disposed onto the light-emitting surface 7 and the N-type common electrode is disposed towards the substrate.
FIG. 2 is a schematic diagram showing an assembled portion of the known LED array head. Thus, when an LED array 13 is assembled onto a ceramic substrate 11 with formed thereon a common electrode wiring 14 and an external wiring 12, the common electrode 6 of the LED is to be coupled to the common electrode wiring 14, and the individual electrode 5 of each LED component is to be coupled to the external wiring 12 by using a gold wire 15, one by one. However, upon the gold wire connection, a total 2048 times of metalic connections will be required to print out an A4-size paper with 240 DPI (Dots per Inch) resolution of commonly used characters, and also a total of 3584 times of metalic connections will be required to print out the same paper with 400 DPI resolution. Further, since the interval between each gold wiring reaches about 100/.mu.m, there will eventually arise a problem that its manufacturing process is difficult and the yield decreased.